4. 3
Contents
1 Binary systems and hexadecimal 2
2 Communication and internet technologies 13
3 Logic gates and logic circuits 18
4 Operating systems and computer architecture 26
5 Input and output devices 30
6 Memory and data storage 38
7 High-and-low level languages 42
8 Security and ethics 48
9 Problem-solving and design 53
10 Pseudocode and flowcharts 59
11 Programming concepts 65
12 Data structures: arrays and using pre-release material 68
13 Databases 75
5. Photocopying prohibited
Cambridge IGCSE Computer Science Workbook
2
1 Binary systems and hexadecimal
1 Convert the denary number 165 into: [3 marks]
a binary
........................................................................................................................................................................
........................................................................................................................................................................
b hexadecimal
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
2 a Convert the following binary number into denary: [6 marks]
0 1 1 1 0 1 1 0
........................................................................................................................................................................
........................................................................................................................................................................
b Convert the following hexadecimal number into denary:
5F
........................................................................................................................................................................
........................................................................................................................................................................
c Convert the following binary number into hexadecimal:
1 0 1 0 1 1 0 0 0 1 0 0
........................................................................................................................................................................
........................................................................................................................................................................
d Convert the following hexadecimal number into binary:
3ED
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
6. Cambridge IGCSE Computer Science Workbook
Photocopying prohibited
3
1
Binary systems and hexadecimal
3 a How many megabytes (MB) of storage would be needed to store 800 photographs
each of which are 16 MB in size? [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
b Write your answer from part a in gigabytes (GB). [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
4 The ASCII code for ‘A’ is 65 and for ‘a’ is 97.
a Write these denary values in 8-bit binary: [2 marks]
i 65
........................................................................................................................................................................
........................................................................................................................................................................
ii 77
........................................................................................................................................................................
........................................................................................................................................................................
b Predict the denary ASCII code for ‘V’ and ‘v’: [2 marks]
i ‘V’
........................................................................................................................................................................
........................................................................................................................................................................
ii ‘v’
........................................................................................................................................................................
........................................................................................................................................................................
c Write the two denary values in part b in 8-bit binary format: [2 marks]
i ‘V’
........................................................................................................................................................................
........................................................................................................................................................................
7. Photocopying prohibited
Cambridge IGCSE Computer Science Workbook
4
1 Binary systems and hexadecimal
ii ‘v’
........................................................................................................................................................................
........................................................................................................................................................................
d Using your answers to part a and part b, suggest an easy way of finding the ASCII binary
code for a lower case letter (e.g. ‘m’) if the ASCII code for the upper case letter (e.g. ‘M’)
is known. [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
5 A computer system uses binary codes for letters of the alphabet as follows:
A = 10, B = 11, C = 12, …… , X = 33, Y = 34, Z = 35
a Write the denary value for ‘X’ in binary using an 8-bit register: [1 mark]
b To convert the binary code for ‘X’ to the binary code for ‘x’, all the bits in the 8-bit register
in part a are moved (shifted) two places to the right.
i Write down the contents of the 8-bit register after the bits have been moved to
the right. [2 marks]
ii Convert the binary value in part bi into denary: [1 mark]
........................................................................................................................................................................
........................................................................................................................................................................
c Predict the denary values for the following two letters using the method described in
part b: [4 marks]
i r
........................................................................................................................................................................
........................................................................................................................................................................
ii m
........................................................................................................................................................................
........................................................................................................................................................................
8. Cambridge IGCSE Computer Science Workbook
Photocopying prohibited
5
1
Binary systems and hexadecimal
6 a Describe how hexadecimal notation is used in the following: [6 marks]
i MAC addresses
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
ii Memory dumps
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
iii HTML
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
b Using the ASCII table (Figure 1.7) on page 12 in the Cambridge IGCSE® Computer Science
textbook, write down what web address/URL is being represented below: [3 marks]
%77%77%77%2E%48%26%53%73%74%75%64%79$20%62%6F%6F%6B%73%2E%63%6F%
2E%75%6B
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
7 a Convert the denary number 44801 into hexadecimal. [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
b Convert the hexadecimal number in part a into a 16-bit binary number. [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
9. Photocopying prohibited
Cambridge IGCSE Computer Science Workbook
6
1 Binary systems and hexadecimal
8 a Explain the two parts that make up a typical MAC address. [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
b A MAC address can be termed either UAA or LAA.
Give two reasons why MAC addresses need to be changed when using LAA. [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
9 An 8-bit register is used to control a paint spray gun. Each position in the register refers to a specific
function:
paint levels
are OK
paint levels
are low
spray gun
switched on
spray gun
switched off
red paint
chosen
green paint
chosen
blue paint
chosen
yellow paint
chosen
A 1 value in the register indicates that a specific function is ON; a 0 value indicates it is OFF.
For example:
1 0 1 0 1 0 1 0
indicates:
• all paint levels are OK
• spray gun is switched on
• red and blue paints have been selected.
a What does the following register indicate: [3 marks]
0 1 0 1 0 0 0 1
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
10. Cambridge IGCSE Computer Science Workbook
Photocopying prohibited
7
1
Binary systems and hexadecimal
b What would be the contents of the 8-bit register if the following conditions existed: [3 marks]
• all paint levels are OK
• the spray gun is switched off
• red and green paint had been selected?
c i What conditions would be represented by: 0 0 0 0 0 0 0 0 ? [1 mark]
........................................................................................................................................................................
........................................................................................................................................................................
ii Describe what would happen if the register contained: 1 1 1 1 1 1 1 1 [1 mark]
........................................................................................................................................................................
........................................................................................................................................................................
10 Six questions are shown on the left and eight numerical values are shown on the right.
By drawing arrows, connect each question to its correct numerical value (two of the
numerical values are not used). [6 marks]
What is the denary value of the
hexadecimal digit ‘E’?
10
22
12
28
14
32
16
40
What is the denary value of the
binary number
0 0 0 1 1 1 0 0 ?
If the download speed for
broadband is 64 megabits per
second, how long would it take to
download a 96 megabyte file (in
seconds)?
If 2x = 1 terabyte (TB), what is the
value of x?
How many bits are there in two
bytes of data?
What is the hexadecimal value of
the denary number 5 0 ?
11. Photocopying prohibited
Cambridge IGCSE Computer Science Workbook
8
1 Binary systems and hexadecimal
11 START
INPUT
number
X ← number
D ← 128
X ← X – D
is X < 0?
OUTPUT
0
X ← X + D
D ← D/2
is D < 1?
STOP
No
No
OUTPUT
1
Yes
Yes
a Trace through the flowchart for the following two values:
i 220 [4 marks]
Number X D OUTPUT
continue on the next page...
12. Cambridge IGCSE Computer Science Workbook
Photocopying prohibited
9
1
Binary systems and hexadecimal
Number X D OUTPUT
ii 73 [4 marks]
Number X D OUTPUT
b State the function of the flowchart in part a. [1 mark]
........................................................................................................................................................................
........................................................................................................................................................................
13. Photocopying prohibited
Cambridge IGCSE Computer Science Workbook
10
1 Binary systems and hexadecimal
12 a The HTML value # FF 00 00 represents the colour red,
value # 00 FF 00 represents the colour green, and
value # 00 00 FF represents the colour blue.
i If the colour orange requires value ‘FF’ for the red hue and value ‘80’ for the green
hue, what is the HTML representation for orange? [1 mark]
........................................................................................................................................................................
ii If the colour tan requires value ‘B1’ for the red hue, value ‘89’ for the green hue and
value ‘04’ for the blue hue, what is the HTML representation for tan? [1 mark]
........................................................................................................................................................................
b Describe how HTML is used when developing web pages. [3 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
c An internet service provider offers the following specifications:
• download speed: 80 megabits per second data transfer rate
• upload speed: 16 megabits per second data transfer rate
i John wishes to download a movie which is 650 megabytes (650 MB) in size. Calculate
how long it would take (in seconds) to download the movie. [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
ii John also wishes to upload 30 photographs onto a social media website. Each photograph is
15 megabytes (15 MB).
Calculate how long it would take to upload the 30 photographs (in seconds). [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
14. Cambridge IGCSE Computer Science Workbook
Photocopying prohibited
11
1
Binary systems and hexadecimal
13 By drawing arrows, connect each term on the left to its correct description on the right. [5 marks]
14 A computer uses a binary system known as Binary Coded Decimal (BCD). In this system, each denary
digit (0 to 9) is represented by a 4-bit binary value:
8 4 2 1
a Give the 4-bit binary codes for the digits 9 and 6. [2 marks]
8 4 2 1
8 4 2 1
b Which denary numbers are represented by the following 4-bit binary codes: [4 marks]
8 4 2 1 8 4 2 1
1 0 0 0 0 1 0 1
....................................................................................
8 4 2 1 8 4 2 1 8 4 2 1
0 1 1 1 0 0 0 0 0 1 0 1
....................................................................................
hypertext mark-up language (HTML) the contents of the computer memory are
output to a screen or printer; this enables
a software developer to locate errors
also identified as a URL such as:
www.books.com
this is used to develop web pages; it is
used in the processing, definition and
presentation of text (e.g. the specification
of a text colour)
value, written in hexadecimal, which is
used to uniquely identify a device on the
network; it is often written in the form:
NN-NN-NN-DD-DD-DD
number system which uses the values 0 to
9 and the letters A to F to represent digits
hexadecimal number system
memory dump
media access control (MAC) address
web address
9
6
15. Photocopying prohibited
Cambridge IGCSE Computer Science Workbook
12
1 Binary systems and hexadecimal
c What is the largest denary number that can be represented by two bytes using this
BCD system? [1 mark]
......................................................................................................................................................................
d Using normal binary notation, what is the largest denary number that could be
represented by two bytes? [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
e Suggest a use for the BCD system. [1 mark]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
15 Write down a series of steps that could be used to convert a denary number into a
hexadecimal number. Your steps should allow somebody to follow them clearly to give the
correct converted value. [7 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
16. Photocopying prohibited
13
Cambridge IGCSE Computer Science Workbook
2 Communication and internet
technologies
1 Name the type and method of data transmission being described below:
a Data transmitted in one direction only; one bit at a time over a single channel or wire. [2 marks]
......................................................................................................................................................................
b Several bits of data transmitted in both directions at the same time over several channels
or wires. [2 marks]
......................................................................................................................................................................
c Data transmitted in both directions, but not at the same time, along a single channel
or wire. [2 marks]
......................................................................................................................................................................
2 a Describe how it is possible to ensure data arrives correctly identified at its destination
when using asynchronous data transmission. [2 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
b Describe how it is possible to ensure that data is received in the correct groups when
using synchronous data transmission. [3 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
c Give one advantage and one disadvantage of using synchronous data transmission. [2 marks]
Advantage: ..................................................................................................................................................
Disadvantage: ..............................................................................................................................................
17. Photocopying prohibited
14
Cambridge IGCSE Computer Science Workbook
3 a Give the meaning of the term USB. [1 mark]
......................................................................................................................................................................
......................................................................................................................................................................
b Indicate with a tick (3) which of the following statements about USB connections
are true: [5 marks]
Statement about USB connections True (3)
All the wires in a USB connector are used in data transmission
The maximum cable length in a USB connection is 2 metres
Devices plugged into the computer using the USB connection are
automatically detected
The USB connection has become the industry standard for most
computers
The user will always be prompted to download a device driver
when the device is plugged in to the computer
c Give two examples of devices which can be connected to a computer using a USB
connection. [2 marks]
1 ...............................................................................................................................................................
2 ...............................................................................................................................................................
4 a A system uses even parity. Indicate which of the following bytes has even parity: [3 marks]
1 1 0 0 0 0 1 1
.......................................................................
0 0 0 1 1 1 1 1
.......................................................................
b Explain why parity checks are used. [1 mark]
........................................................................................................................................................................
........................................................................................................................................................................
i
iii
1 0 1 1 0 1 1 0
.......................................................................
ii
2 CommuniCation and internet teChnologies
18. Photocopying prohibited
15
Cambridge IGCSE Computer Science Workbook
2 Communication and internet technologies
c Nine bytes of data were transmitted from one computer to another computer. Even parity was
used by both systems. An additional byte, called the parity byte was also sent at the end of the
transmission.
The following table shows the nine bytes and parity byte following transmission:
parity bit bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 bit 8
byte 1 1 1 1 0 1 1 1 0
byte 2 1 0 0 0 0 1 0 0
byte 3 0 1 1 1 0 0 1 0
byte 4 0 1 1 1 1 0 1 1
byte 5 1 1 0 0 0 1 1 0
byte 6 0 1 1 0 1 1 0 1
byte 7 1 0 0 1 0 0 0 0
byte 8 0 1 1 1 1 1 0 1
byte 9 0 0 0 0 1 0 0 1
parity byte: 0 0 1 1 1 1 0 0
i One of the bits has been transmitted incorrectly. Indicate which bit is incorrect by
giving its bit number and byte number: [2 marks]
bit number: ........................................................................................................................................
byte number: .....................................................................................................................................
ii Explain how you arrived at your answer to part ci. [3 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
iii Write down the corrected byte: [1 mark]
......................................................................................................................................................................
iv Describe a situation where a parity check would not identify which bit had been
transmitted incorrectly. [2 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
19. Photocopying prohibited
16
Cambridge IGCSE Computer Science Workbook
2 CommuniCation and internet teChnologies
v Name and briefly describe another method to check if data has been transmitted
correctly. [2 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
5 Which internet terms are being described below? [5 marks]
Companies that provide the user with access to the
internet; a monthly fee is usually charged for this
service
A unique address that identifies the location of a
device which is connected to the internet
A unique address that identifies the device that is
connected to the internet
A set of rules that must be obeyed when transferring
files across the internet
Software that allows a user to display a web page on
their computer screen; they translate the HTML from
the website
6 a HTML is made up of structure and presentation. Explain the difference between these
two terms. [3 marks]
Structure:......................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
Presentation: ................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
b Indicate how you would know whether or not a website was secure. [1 mark]
......................................................................................................................................................................
......................................................................................................................................................................
20. Photocopying prohibited
17
Cambridge IGCSE Computer Science Workbook
2 Communication and internet technologies
7 Look at the following two HTML parts:
Part A
Part B
a Which of the above parts shows the .css file? [1 mark]
..............................................................................
b Using parts A and B from above, give two examples of tags. [2 marks]
......................................................................................................................................................................
c Show how a tag is closed. [1 mark]
......................................................................................................................................................................
d Explain why there are three groups of data in the color definition. [1 mark]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
e Which number base is used to represent values in the color definition? [1 mark]
......................................................................................................................................................................
21. Photocopying prohibited
18
Cambridge IGCSE Computer Science Workbook
3 Logic gates and logic circuits
1 Which logic gates have the following three truth tables? [3 marks]
a
A B X
0 0 0
0 1 1
1 0 1
1 1 1
...........................
2 Complete the truth table for the following logic circuit: [4 marks]
A
B
C
X
A B C Working area X
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
3 a Write the following statement as a logic statement: [3 marks]
X is 1 if A and B are on or if B is off and C is on
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
b A B X
0 0 1
0 1 1
1 0 1
1 1 0
...........................
c A B X
0 0 0
0 1 1
1 0 1
1 1 0
...........................
22. Photocopying prohibited
19
Cambridge IGCSE Computer Science Workbook
3 Logic gates and logic circuits
b Draw the logic circuit to represent your statement in part a. [4 marks]
A
B
X
C
4 a Complete the truth table for the following logic circuit: [2 marks]
A
B
X
A B Working area X
0 0
0 1
1 0
1 1
b Which single logic gate is represented by the truth table in part a? [1 mark]
......................................................................................................................................................................
c Explain why a single logic gate is often replaced by a logic circuit such as the one shown
in part a. [1 mark]
......................................................................................................................................................................
......................................................................................................................................................................
23. Photocopying prohibited
20
3 Logic gates and Logic circuits
Cambridge IGCSE Computer Science Workbook
5 a Complete the truth table for the following logic circuit: [4 marks]
A
B
C
X
A B C Working area X
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
b Which simplified logic circuit could replace the logic circuit in part a? [1 mark]
......................................................................................................................................................................
6 a Complete the truth table for the following logic circuit: [4 marks]
A
B
C
X
24. Photocopying prohibited
21
Cambridge IGCSE Computer Science Workbook
3 Logic gates and logic circuits
A B C Working area X
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
b What single logic gate could replace the following logic circuit? [2 marks]
.......................................................................................................................................................................
7 a Write down the logic statement to represent the following logic circuit: [3 marks]
A
B
C
X
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
25. Photocopying prohibited
22
3 Logic gates and Logic circuits
Cambridge IGCSE Computer Science Workbook
b Draw the logic circuit which corresponds to the following truth table: [4 marks]
A B C X
0 0 0 1
0 0 1 0
0 1 0 1
0 1 1 1
1 0 0 1
1 0 1 0
1 1 0 1
1 1 1 1
A
B X
C
8 A chemical process is monitored using a logic circuit. There are three inputs to the logic circuit
representing the parameters being monitored in the chemical process. An alarm, X, will give an
output value of 1 depending on certain conditions.
The following table describes the process conditions being monitored:
Parameter description Parameter Binary
value
Description of condition
reaction temperature T 0 temperature > 120°C
1 temperature <= 120°C
pressure of CO gas evolved P 0 pressure > 2 bars
1 pressure <= 2 bars
acid concentration A 0 acid concentration > 4 moles
1 acid concentration <= 4 moles
An alarm, X, will generate the value 1 if:
• either temperature > 120°C and acid concentration <= 4 moles
• or temperature <= 120°C and gas pressure <= 2 bars
• or acid concentration > 4 moles and gas pressure <= 2 bars
26. Photocopying prohibited
23
Cambridge IGCSE Computer Science Workbook
3 Logic gates and logic circuits
a Write the logic statement to represent this system. [3 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
b Draw the logic circuit to represent this system. [7 marks]
T
A X
P
c Complete the truth table to represent this system. [4 marks]
T A P Working area X
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
27. Photocopying prohibited
24
3 Logic gates and Logic circuits
Cambridge IGCSE Computer Science Workbook
9 A safety system uses the input from three sensors A, B and C. The binary values from these sensors
form the input to a logic circuit.
Logic circuit ‘X’ Output, X, from logic circuit
Sensor A
Sensor B
Sensor C
The output, X, from the logic circuit is 1 if:
• either A is 1 and B is 1
• or A is 0 and C is 1
• or B is 0 and C is 1
a Draw the logic circuit to represent the above system. [7 marks]
A
B X
C
b Complete the truth table for the above system. [4 marks]
A B C Working area X
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
28. Photocopying prohibited
25
Cambridge IGCSE Computer Science Workbook
3 Logic gates and logic circuits
c For safety reasons, the sensors feed into three different logic circuits (numbered 1, 2 and 3) which
produce the outputs X, Y and Z. These three outputs then form the inputs to another logic circuit
that has the output, Q.
The three logic circuits are connected to this extra logic circuit as shown below:
Logic
circuit 1
Output X
Output Y
Q
Output Z
Logic
circuit 2
Logic
circuit 3
inputs
from
the
three
sensors
A, B
and C
Complete the truth table for this system. [4 marks]
X Y Z Working area Q
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
29. Photocopying prohibited
26
Cambridge IGCSE Computer Science Workbook
4 Operating systems and
computer architecture
1 Give six functions of a typical operating system (OS). [6 marks]
1 .................................................................................................................................................................
2 .................................................................................................................................................................
3 .................................................................................................................................................................
4 .................................................................................................................................................................
5 .................................................................................................................................................................
6 .................................................................................................................................................................
2 a Describe three different types of interrupt. [3 marks]
1 .................................................................................................................................................................
.................................................................................................................................................................
2 .................................................................................................................................................................
.................................................................................................................................................................
3 .................................................................................................................................................................
.................................................................................................................................................................
b What is meant by the term buffer? [1 mark]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
c The flowchart on the opposite page shows how buffers and interrupts are used when the
processor sends data to a printer. Some of the items are missing from the flowchart.
Using item numbers only, complete the flowchart using the following list of items: [6 marks]
Item number Item
1 contents of printer buffer emptied to printer
2 current task is suspended while interrupt is serviced
3 data to be printed out is sent to the printer buffer
4 processor continues with its current tasks
5 processor continues with current tasks while printer buffer is emptied
6 when all the data is printed, printer buffer becomes empty
30. Photocopying prohibited
27
Cambridge IGCSE Computer Science Workbook
4 Operating systems and computer architecture
Any data to
be sent to
printer?
No
No
All data
sent to
printer?
Interrupt signal is
sent to request
more data to be
sent to printer
Yes
Yes
3 a Name three types of bus used in the von Neumann architecture. [3 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
b Name three types of address used in the von Neumann architecture. [3 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
31. Photocopying prohibited
28
4 Operating systems and cOmputer architecture
Cambridge IGCSE Computer Science Workbook
c The memory contents of a computer are shown below.
Address Contents
1000 0000 0111 1100
1000 0001 1000 0011
1000 0010 1111 1101
1000 0011 0111 1110
1000 0100 1100 1101
1111 1100
1111 1101 0110 0011
1111 1110 1010 0111
1111 1111 1111 0011
i Show the contents of the MAR and MDR if we want to READ the contents of memory
location 1 1 1 1 1 1 1 0. [2 marks]
MAR:
MDR:
ii Show the contents of the MAR and MDR if we wish to write 1 1 0 0 1 1 0 1 into memory
location 1 0 0 0 0 1 0 0. [2 marks]
MAR:
MDR:
iii If MAR contains 1 1 1 1 1 1 0 0 and MDR contains 0 0 1 1 1 1 0 0, fill in the shaded
cell of the memory contents diagram above. [1 mark]
4 The diagram on the opposite page shows a typical fetch–execute cycle; however, five of the stages
have been omitted. Complete the cycle by writing the following stages in their correct position.
Stage Description of stage
1 Address is then copied from PC to MAR via the address bus
2 Contents of memory location contained in MAR are then copied into MDR
3 Instruction is decoded and then executed by sending out signals via control bus to
the computer components
4 The PC contains the address of memory location of the next instruction to be
fetched
5 Value of PC is then incremented by 1 so it now points to the next instruction to be
fetched
[5 marks]
32. Photocopying prohibited
29
Cambridge IGCSE Computer Science Workbook
4 Operating systems and computer architecture
Contents of MAR are then copied and placed in the CIR
5 a Explain why some devices do not need to have an operating system. [2 marks]
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
......................................................................................................................................................................
b Give an example of a device which does not require an operating system. [1 mark]
......................................................................................................................................................................
33. Photocopying prohibited
30
Cambridge IGCSE Computer Science Workbook
5 Input and output devices
1 Describe how face recognition software is used at an airport to verify the identity of
passengers. [4 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
2 Explain each of the following scanner terms. [6 marks]
CCD: ................................................................................................................................................................
.........................................................................................................................................................................
.........................................................................................................................................................................
CT: ...................................................................................................................................................................
.........................................................................................................................................................................
.........................................................................................................................................................................
MRI: ................................................................................................................................................................
.........................................................................................................................................................................
.........................................................................................................................................................................
3 a A barcode showing three digits is shown below.
A B
1
C
34. Photocopying prohibited
31
Cambridge IGCSE Computer Science Workbook
5 Input and output devices
Give the binary value of each digit. [3 marks]
A: ...............................................................................................................................................................
B: ...............................................................................................................................................................
C: ...............................................................................................................................................................
b A supermarket uses barcodes on all its items. When a customer goes to check out, a number of
input and output devices may be used.
Name two input devices and two output devices. Give a different use for each named
device. [8 marks]
Input device 1: ..........................................................................................................................................
Use: ...........................................................................................................................................................
....................................................................................................................................................................
Input device 2: ..........................................................................................................................................
Use: ...........................................................................................................................................................
Output device 1: .......................................................................................................................................
Use: ...........................................................................................................................................................
....................................................................................................................................................................
Output device 2: .......................................................................................................................................
Use: ...........................................................................................................................................................
....................................................................................................................................................................
c Give two benefits to the supermarket manager and two benefits to customers of using
barcodes on all items. [4 marks]
Manager
1 .................................................................................................................................................................
....................................................................................................................................................................
2 .................................................................................................................................................................
....................................................................................................................................................................
Customer
1 .................................................................................................................................................................
...................................................................................................................................................................
2 .................................................................................................................................................................
....................................................................................................................................................................
35. Photocopying prohibited
32
5 Input and output devIces
Cambridge IGCSE Computer Science Workbook
3 The barcode on the right is known as a QR code:
a What does ‘QR’ mean? [1 mark]
......................................................................................................................................................................
b Give two benefits of using QR codes. [2 marks]
1 .................................................................................................................................................................
................................................................................................................................................................
2 .................................................................................................................................................................
................................................................................................................................................................
c Explain how a tourist could use QR codes at an airport to help plan a holiday. [3 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
4 Give the most suitable input device for each of the following applications. A different
device must be given in each case. [5 marks]
Application Suitable input device
Entering text and data into a word processor or
spreadsheet
Selecting an option or icon from an onscreen menu
Input a user’s voice into a computer as part of a voice
recognition system
Converting a hard copy document into an electronic
form to be stored in a computer
System that allows a user to write and draw on a screen
which then automatically saves the text and images in
a memory
36. Photocopying prohibited
33
Cambridge IGCSE Computer Science Workbook
5 Input and output devices
5 a Inkjet printers usually fall into two categories: thermal bubble or piezoelectric.
Choose one of these categories and describe how ink droplets are produced. [3 marks]
Category: ........................................................................................................................................................
........................................................................................................................................................................
Description: ....................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
b Give one advantage and one disadvantage of inkjet printers compared with laser
printers. [2 marks]
Advantage: ....................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
Disadvantage: ................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
c The diagram on the following page shows the steps carried out when an inkjet printer prints a
document.
The steps have not been written in the correct order. By writing the numbers 1 to 9 next to each
step, place them in the correct order.
The first one has been done for you. [8 marks]
37. Photocopying prohibited
34
5 Input and output devIces
Cambridge IGCSE Computer Science Workbook
Steps Order
The printer driver checks whether the chosen printer is ready to print the document
Once the printer buffer is empty, the printer sends an interrupt to the processor
requesting more data to be sent; this action continues until the whole document is
printed
A sheet of paper is fed into the printer body; if no paper is available or the paper is
jammed, an error message is sent to the computer
At the end of each full pass of the print head, the paper is advanced slightly to allow
the next line to be printed
The printer driver ensures that the data is in a format that the chosen printer can process
Data is sent to the printer and is stored in a temporary memory, known as the printer
buffer
Data from the document is first of all sent to the printer driver 1
As a sheet of paper is fed through the printer, the print head moves from side to side
printing text/image in the four colours
The whole process is continued until the printer buffer is empty
6 a 3D printers use various ways to produce solid objects. Explain each of the following
terms: [3 marks]
Additive: .........................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
Direct 3D printing: .........................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
Binder 3D printing: ........................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
38. Photocopying prohibited
35
Cambridge IGCSE Computer Science Workbook
5 Input and output devices
b A car enthusiast has bought a car made in 1921. Unfortunately, none of the parts for the car are
still made.
Explain how 3D technology could be used to create any part for this car. [3 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
c Describe three other uses of 3D printers. [3 marks]
1 .................................................................................................................................................................
....................................................................................................................................................................
....................................................................................................................................................................
2 .................................................................................................................................................................
....................................................................................................................................................................
....................................................................................................................................................................
3 .................................................................................................................................................................
....................................................................................................................................................................
....................................................................................................................................................................
7 a Most modern televisions and computer screens are LCD and use LED back-lit technology.
Give three advantages of using LED back-lit technology rather the older CCFL
(fluorescent lamp) technology. [3 marks]
1 .................................................................................................................................................................
....................................................................................................................................................................
2 .................................................................................................................................................................
....................................................................................................................................................................
3 .................................................................................................................................................................
....................................................................................................................................................................
39. Photocopying prohibited
36
5 Input and output devIces
Cambridge IGCSE Computer Science Workbook
b i Explain the term OLED. [1 mark]
........................................................................................................................................................................
........................................................................................................................................................................
ii Give two benefits of using OLED technology rather than LCD. [2 marks]
1.............................................................................................................................................................
...............................................................................................................................................................
2 ............................................................................................................................................................
...............................................................................................................................................................
8 Describe a suitable different application that uses each of the following sensors. [4 marks]
Sensor Application
temperature
light
infrared
magnetic field
40. Photocopying prohibited
37
Cambridge IGCSE Computer Science Workbook
5 Input and output devices
9 A burglar alarm system uses pressure sensors and acoustic (sound) sensors to detect the presence of
an intruder.
A microprocessor is used to monitor and control the whole system. A keypad is used to key in a
4-digit PIN that either activates or deactivates the system.
If an intruder is detected, an alarm is sounded and also a blue flashing light outside the building.
Describe in detail how the sensors and microprocessor interact to detect and warn of
an intruder. [7 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
41. Photocopying prohibited
38
Cambridge IGCSE Computer Science Workbook
6 Memory and data storage
1 Five file terms are shown on the left and five file descriptions are shown on the right.
By drawing arrows link each file term to its correct file description. [5 marks]
MP3 file
BMP file
MIDI file
jpeg image
lossy file format
uses compression technology to reduce
the size of an image
uses compression technology to reduce
the size of a music file by up to 90%
file compression algorithm that reduces
file size by eliminating unnecessary bits
of data
a raw bitmap image that has not yet been
compressed
communication protocol that allows
electronic musical instruments to interact
with each other
2 a Give three differences between RAM and ROM memories. [3 marks]
1 .................................................................................................................................................................
...................................................................................................................................................................
...................................................................................................................................................................
2 .................................................................................................................................................................
...................................................................................................................................................................
...................................................................................................................................................................
3 .................................................................................................................................................................
...................................................................................................................................................................
...................................................................................................................................................................
b Two types of RAM are DRAM and SRAM. In the diagram below, draw arrows to link
each type of RAM to its correct feature(s). [5 marks]
DRAM
SRAM
needs to be constantly refreshed to retain
the data
consumes the least power of the two
types of RAM
makes use of ‘flip flops’ to hold bits of
memory
used in computers where high speed
processing is needed; e.g. memory cache
has the higher storage capacity of the two
types of RAM
42. Photocopying prohibited
39
Cambridge IGCSE Computer Science Workbook
6 Memory and data storage
3 a Give an example of data which matches the data formats below. [3 marks]
Real: ................................................................................................................................................................
Integer: ...........................................................................................................................................................
Currency: ........................................................................................................................................................
b i Assuming each character is 1 byte in size, and ignoring spaces, how many bytes of
memory would be needed to store the following sentence? [1 mark]
‘this shows you how lossless would use less memory’............................................
ii A file compression system replaces parts of the text in the sentence as follows:
th = 1, is = 2, how = 3, ou = 4, less = 5
Rewrite the sentence in part bi using the above numerical values where possible. [2 marks]
......................................................................................................................................................................
......................................................................................................................................................................
iii How many bytes of memory does your new sentence in part bii require? [1 mark]
......................................................................................................................................................................
iv Explain why the method described in part bii is lossless compression. [1 mark]
......................................................................................................................................................................
......................................................................................................................................................................
4 a Place each of the following storage and memory devices into their correct category: [6 marks]
• Blu-ray disc
• DVD-RAM
• Fixed hard-disk drive (HDD)
• Fixed solid-state drive (SSD)
• Flash memory/memory stick
• RAM
• Removable hard-disk drive (HDD)
• ROM
Primary Secondary Off-line
43. Photocopying prohibited
40
6 MeMory and data storage
Cambridge IGCSE Computer Science Workbook
b Give three advantages of using SSD rather than HDD in a computer system. [3 marks]
1 .................................................................................................................................................................
....................................................................................................................................................................
2 .................................................................................................................................................................
....................................................................................................................................................................
3 .................................................................................................................................................................
....................................................................................................................................................................
5 a The following table shows six features of optical media. By placing ticks (3) in the
correct boxes, indicate which features refer to which optical media. [3 marks]
Optical media Use red lasers
to read/write
Use blue
lasers to
read/write
Use two
polycarbonate
layers
Use one
polycarbonate
layer
Track pitch
< 1µm
Track pitch
> 1µm
CD
DVD
Blu-ray
b Describe three advantages of using Blu-ray discs rather than normal DVDs to
store movies. [3 marks]
1 .................................................................................................................................................................
....................................................................................................................................................................
....................................................................................................................................................................
2 .................................................................................................................................................................
....................................................................................................................................................................
....................................................................................................................................................................
3 .................................................................................................................................................................
....................................................................................................................................................................
....................................................................................................................................................................
44. Photocopying prohibited
41
Cambridge IGCSE Computer Science Workbook
6 Memory and data storage
6 A student wrote: ‘The future of optical media is one of obsolescence in the next five years’.
Discuss this statement by reference to modern technologies. [3 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
45. Photocopying prohibited
42
Cambridge IGCSE Computer Science Workbook
7 High- and low-level languages
1 What is a program? [2 marks]
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
........................................................................................................................................................................
2 The following terms are used about high-level programming languages. [3 marks]
State what each term means.
a Portable
........................................................................................................................................................................
........................................................................................................................................................................
b Problem solving
........................................................................................................................................................................
........................................................................................................................................................................
c Translation
........................................................................................................................................................................
........................................................................................................................................................................
3 Give four examples of high-level programming languages. [4 marks]
1 ......................................................................................................................................................................
2 ......................................................................................................................................................................
3 ......................................................................................................................................................................
4 ......................................................................................................................................................................